A new method has been established to study cartilage breakdown in vivo. Cartilage was implanted into air pouches on the backs of mice or rats and loss of proteoglycan measured biochemically. Using the air pouch it was possible to produce various inflammatory environments either immune or non immune and examine the effects of these upon proteoglycan loss. It was found that the various type of inflammation failed to accelerate proteoglycan loss from implanted cartilage. Subsequently a variety of drugs used in the treatment of the arthropathies were examined for their effect on both inflammation and cartilage breakdown. Using xiphisternum a difference could be shown between non-steroidal anti-inflammatory drugs (NSAID) and d-penicillamine in that, NSAID failed to protect the cartilage whereas d-penicillamine prevented proteoglycan loss. This type of cartilage was not examined further, as it was not characteristic of articular cartilage - being surrounded by perichondrium. Later articular cartilage was implanted once again into different inflammatory situations and drug effects evaluated. It was found using this cartilage that all the drug 0 used protected from loss of proteoglycan and whereas some inhibited inflammation (indoniethacin and dexamethasohe), 2a levamisole had no effect in contrast, d-penicillamine potentiated the inflammatory response. Finally the mode of action of the drugs in this method is discussed.